Wireless system



Sept- 1934. w. LEWIS 1,972,387 WIRELESS SYSTEM Filed April 8, 1929 2 Sheets-Sheet l INVENTOR Wll LIAM m gjvofi LEI v15 m ATTO RNEY p 1934. w. LEWIS 1,972,387

' I WIRELESS SYSTEM Filed April 8, 1929 2 Sheets-Sheet 2 V V INVENTOR ATTORN EY Patented Sept. 4, 1934 UNITED STATES PATENT OFFICE 9 Claims.

This invention is directed to wireless systems, and is particularly directed to a wireless receiving system in which a screened grid tube is employed.

In screened grid tubes a very large amplification Constant is obtained, but it is necessary to maintain certain definite adjustments to secure the maximum benefit from the increased amplification obtained by these tubes.

In the prior attempts to use these tubes it has been found that when the plate voltage is adjusted, the voltage impressed upon the screen is not always of the correct value and, consequently, the tube does not function to the best advantages, and also frequently produces disturbance and unwanted effects in this system.

This invention is designed to overcome the defects noted above, and objects of this invention are to provide a novel form of wireless receiving system in which means are provided for simultaneously varying the voltage impressed on the screen and the voltage impressed on the plate of each of the several tubes of the system.

Further objects are to provide a novel form of wireless receiving system in which a simple adjustment is all that is required of the operator, such adjustment varying the plate voltage to the desired extent, and without a thought on the part of the operator, also varying the voltage impressed upon the screen.

A further object of this invention is to provide a wireless receiving system which is so constructed that the plate voltage and the screen voltage may be simultaneously varied by a single instru mentality for a large number of screened grid tubes.

Further objects are to provide a construction in which provision is made for impressing a lower voltage on some one or more'of the plates of the tubes and simultaneously controlling this voltage and the voltages impressed on the screens and plates of other tubes.

It has been found thatscreened grid tubes, under certain conditions, have a pronounced hiss, which is particularly noticeable when several tubes are used in cascade.

This invention has for a further object the provision of means for controlling screened grid tubes in asimple andeasy manner to'effectually prevent hissing even when a plurality of screened grid tubes are employed, by an accurate and proper control of the voltage or voltages impressed upon the plates and screens. a

It is sometimes found that reception is weak at certain dial settingsjan'd a'further object of this invention is to provide a control for screened grid tubes which may be readily attached to the main tuning control to thereby compensate for any weak response at certain places on the main tuning .dial.

Further objects are to provide a very simple apparatus for accomplishing the above noted results, and one which may be cheaply manufactured and easily applied to wireless receiving systems.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a diagrammatical view showing screened grid tubes connected to and associated with the controlling apparatus.

Figure 2 is an elevation partly in section of one form which the control device may take.

Figure 3 is a diagrammatical view of a further form of control device.

Figure 4 is a view showing a further form of the invention in which the plates of the radio frequency tubes have different voltages impressed thereon, and in which these diflerent voltages are simultaneously controlled with the screen voltages.

Referring to the drawings, particularly Figure 1, it will be seen that two screened grid tubes 1 and 2 have been illustrated, and it is intended that any number of the tubes may be used with this system as occasion may demand. The tubes are each equipped with a grid 3, a filament 4, a plate 5, and a screen 6. The grid of the first tube is connected in any desired manner with an input circuit, which may include the secondary coil '7 and a variable condenser 8. The coil and condenser may be in parallel, and one end of each may be connected to the filament bus-bar 9. The plate of each tube is connected through the primary 1'0.of' aradio frequency coupling device to the plate bus-bar 10. The secondary coil 11 may connect to the grid of a succeeding tube, and, this secondary may be tuned by means of a variable condenser, as indicated at 12 in Figure 1. The screens 6 of each of the tubes are connected to a screen bus-bar 13. It is preferable to provide'condensers as indicated at 14 between the filament and the screen of each of the tubes, and it is. also preferable toprovide a condenser 15 between the bus-bars 9 and 10.

Itis apparent that although specific connections have been described in detail, that other systems could be followed without departing from the spirit of the invention, as the invention is primarily directed to the means for simultaneously-varyingthe voltage impressed upon the of the B battery 16 is connected to one end of screen and plate of each of the screened grid tubes. The means for accomplishing this result may take various forms. In the form shown in Figure 1, the B battery 16 has itsnegative terminal connected to the bus-bar 9, and its positive terminal connected to one end of a resistance 17. The resistance is connected at an intermediate point to the plate bus-bar 10 by means of the contact member indicated diagrammatically at 18 in Figure 1. An intermediate point a variable resistance 19. An intermediate point of this resistance is connected by means of the. contact 20 to the screen bus-bar 13. The con tact members 18 p and 20 are simultaneously moved, as diagrammatically indicatedin Figurevariable resistances l7 and19 may take various forms. One form is indicated in Figure 2. In this form of the inventionthe resistances-17 and 19 are carried by insulating plates .21 and 22 respectively, and are engaged by the sliding contacts 18- and 20, see Figure 2-.- These contacts may be carried by slip rings 23 and 24 respectively, whichare engaged by brushes 25 and 26. Each slip ring is provided with an insulated bushing 27, which electrically insulates the ring from the shaft 28. The shaft 28-may be provided with an insulating knob or other member 29 by means of whichthe. resistances may be adjusted.

It is apparent that when the plate voltage is adjusted by turning the knob 29, simultaneously the screenivoltage is varied in a proportionate manner.

In a modified form of theinvention, illustrated in Figure 3, a fixed resistance 30 is connected at one end to the B battery 16 and at its other end is connectedvthrough a variable resistance 31 to the other end of the Bbatt-ery.- A suitable intermediate point of the resistance 30 is connected to the screen bus-bar 13 by means of the conpriate point intermediate the ends ofthe'fixed resistance 30.. After this selection has been made, it is clear that an adjustment of the rheostat 31 will simultaneously proportionately vary the voltages impressed upon the screens and upon the plates of these several tubes.

It will be seen that the rheostat or adjusting member maytake several different forms, as illustrated, for example in Figures 2 and 3 of the drawings. These illustrations are intended merely as examples and are not-intendedas in any way limitingthe invention other than as claimed. In the form of the invention shown in Figure 4, thesame inventive idea is. followed except that a lower voltage is impressed on the plate of one or more of the radio. frequency tubes from that impressed onmthe plates of the .otherradio frequency tubes. V Q

. In this modified form of the..invention, the

limiting in any sense. 1

tubes 34, 35, and 36 are radio frequency tubes, and the tube 37 is a detector. The grid circuit of the tube 34 is coupled to the antenna in any suitable manner as by means of the coil 7, and this circuit is tuned by means of the condenser 48, for example. The plate 38 of this tube is connected through the primary 39 of a radio frequency coupling device to the bus-bar 40. The plates 41 and 45 of the tubes 35 and 36 are connected through the primaries,.,43 and 47 of their respective coupling devices to the bus-bar 44. The screens 42 and 46 of the tubes 35 and 36 are connected to the bus-bar 40. Resistances 17 and 19 are connected to higher and lower voltage points of the plate supply, such as a B battery or; B battery eliminator, and are respectively connected by the movable contact members 18' and 20 to the bus-bars 44 and 40 respectively. The contact members 18' and 20 are mechanically connected, or simultaneously controlled, so that the voltages impressed upon the plates and screens of the tubes are simultaneously controlled. It isto be notedthat although. one or more of the tubes has a lesser voltage impressed on its plate than the other tubes, nevertheless its voltage is also simultaneously controlled with that impressed upon the plates and screens of other tubes.

Similarly to the grid circuit of the tube 34, the grid circuits of the tubes 35, 36, and 37 may be tuned, if desired, and it is preferable to provide means for simultaneously. tuningall of, the grid circuits as shown in-Figure 4. For instance, the grid circuits of the tubes 34, 35, 36, and 37 may be provided with variable condensers 48,

49, 50, and 51, respectively, and these condensers may be simultaneously. operated by a master member as shown diagrammatically in the figure.

Thus, it is clear that this invention lends itself to a very simple form of circuit in which means are provided for the simultaneous control of the screen voltage andthe plate voltage of a plurality of tubes, although some one or more of the tubes may have a lower voltage impressed on the plates than other of the tubes.

Further, no thought is required of the oper.

ator in manipulating the voltage control, for such control simultaneously proportionately adjusts the voltage of the plates and screens of any desired number of tubes. Thus, the best operating conditions-are obtained, without any effort on the part of the operator, and the'proper voltage for the several screens is automatically obtained with each adjustment. of the plate voltage.

It will be seen that a very simple form of wireless receiving system' has been provided by this invention, which is admirablyadapted to the use of screenedfgrid tubes, and which provides ,a

simple, reliable andletfectiv e means of simultaneously varying the voltageimpressed upon the screen and the plate of eithera single vacuum ub or p ral t 0i rwuumfiub sl I Y 7 It is to be distinctly understood that {in the description and in the. claims .the-expression filament is intended to cover either a filament or any form of cathodegwhether of the iorm shownor of the equipotential-type, for; the invention is applicable to either D. dyer? A. C.

tubes. The use of theterml l filamenti and'the showing in thedrawings are; merely for thesake of simplicity, and are not toflbe construed as Itis within the r vince of this a tar to operativelyconnect any of the voltage control devices and the main tuning control in any form of the invention, so that the voltage impressed upon the plates and screens can be automatically varied by the tuning control to compensate for weak signals at any setting of the main tuning control. For instance, the shaft 28, Figure 2, could be operatively connected to the main tuning control. This construction is diagrammatically indicated in Figure 4.

It is, of course, to be understood that any type of tubes could be used with the screened grid tubes and could be located at any portion of the system desired.

It is to be understood that although several different forms of control and different systems have been shown and described, any form of control may be used with any system. Further, although the invention has been described as particularly directed to a receiving system, the method of controlling the voltages of the plates and screens is equally applicable to transmitting systems.

Although the invention has been described in considerable detail, it is intended that this description be interpreted as illustrative, as the invention may be variously embodied and is, as stated, to be interpreted as claimed.

I claim:

1. In a Wireless receiving system, the combination of a plurality of screened grid tubes each having a plate, a filament, a grid, and a screen; coupling means between said tubes; input and output circuits; means for impressing voltage on the plate and screens of said tubes and means for simultaneously varying the voltage impressed upon the plate and screen of each of said tubes.

2. In a wireless receiving system, the combination of a plurality of screened grid tubes each having a plate, a filament, a grid, and a screen; coupling means between said tubes; input and output circuits; a common bus-bar connecting each of said screens; a common bus-bar supplying each of said plates; and means connected to said bus-bars for simultaneously varying the voltage impressed upon the plate and screen of each of said tubes.

3. In a wireless receiving system, the combination of a plurality of screened grid tubes each having a plate, a filament, a grid, and a screen; coupling means between said tubes; input and output circuits; a common bus-bar connecting each of said screens; a common bus-bar supplying each of said plates; and means connected to said bus-bars for simultaneously and proportionately varying the voltage impressed upon the plate and screen of each of said tubes.

4. In a wireless receiving system, the combination of a plurality of tubes having plates, grids,

and filaments, certain of said tubes having screens; coupling means between said tubes; input and output circuits; means for impressing voltage upon the plates and screens and means for simultaneously varying the voltage impressed upon the plates and screens of the tubes which are provided with screens, the voltage impressed upon the plate of at least one of said tubes being different from the voltage impressed upon the plate of another of the tubes.

5. In a wireless receiving system, the combination of a group of tubes having plates, filaments, and grids, certain of said tubes having screens; coupling means between said tubes; input and output circuits; means for impressing different voltages upon the plates of certain of said tubes; means for impressing voltages upon said screens;

and means for simultaneously varying the said voltages.

*6. In a wireless receiving system, the combination of a plurality of tubes, each tube having a plate, a filament, and a grid, and certain of said tubes being of the screened grid type, coupling means between said tubes, said tubes having input and output circuits, means for tuning certain of said circuits, and means operatively connected to said tuning means for simultaneously varying the voltage impressed upon the plate and screen of at least one of said screened grid tubes.

7. In a wireless receiving system, the combination of a plurality of tubes having plates, grids, and filaments, certain of said tubes having screens; coupling means between said tubes; input and output circuits; means for impressing voltage upon the plates and screens and means for simultaneously varying the voltage impressed upon the plates and screens of the tubes which are provided with screens without varying the voltage impressed upon the plate of another of said tubes.

8. In the operation of a radio receiving system comprising a tube of the screen grid type, a method of control which comprises simultaneously varying the platevoltage of the tube and the biasing voltage of a grid of the tube in such senses and to such relative extents that the internal plate impedance of the tube is varied to an extent differing from that caused by variation of the plate voltage alone.

9. Radio receiving apparatus comprising a tube of the screen grid type, means for varying the plate voltage of said tube, and means for simultaneously varying the biasing voltage of a grid of said tube, in such senses and to such extents that the internal plate impedance of the tube is varied to an extent differing from that caused by the variation of plate voltage.

WILLIAM TURNOR LEWIS. 

